Home/CVE/NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path
CVE

CVE-2026-39844

NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path

NiceGUI is a Python-based UI framework. Prior to 3.10.0, Since PurePosixPath only recognizes forward slashes (/) as path separators, an attacker can bypass this sanitization on Windows by using backslashes (\) in the upload filename. Applications that construct file paths using file.name (a pattern demonstrated in NiceGUI's bundled examples) are vulnerable to arbitrary file write on Windows.

This vulnerability is fixed in 3.10.0.

MEDIUM · CVSS 5.9 EPSS 0.00064
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules7 YARA rules0
⬡

Weakness Classification

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
▤

Affected Products & Versions

1
zauberzeug nicegui< 3.10.0
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI nicegui MODERATE fixed in 3.10.0
◈

Sigma Hunt Rules

7
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productcriticalHackTool - Windows Credential Editor (WCE) Execution
productcriticalWindows Credential Editor Registry
producthighOpenCanary - MSSQL Login Attempt Via Windows Authentication
producthighWindows LAPS Credential Dump From Entra ID
producthighTamper Windows Defender - PSClassic
producthighTamper Windows Defender Remove-MpPreference - ScriptBlockLogging
▣

Scoring & Timeline

5.9
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD08 Apr 2026 · 09:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/zauberzeug/nicegui/commit/d38a702e3af2da5b0708f689be8d71413fc77056Patch
https://github.com/zauberzeug/nicegui/releases/tag/v3.10.0Release Notes
https://github.com/zauberzeug/nicegui/security/advisories/GHSA-w8wv-vfpc-hw2wVendor Advisory
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